A Solution to Personal Housing Woes: Personal Tents!
I've just had THE BEST idea, everyone will agree :)
Implement personal tents (or caravans)!
The tents would be small (tiny??) instanced rooms that can be decorated as players like. The tent would be on a plot with enough space for a 4-bed garden patch and a stake to tie up your chocobo; possibly room for 1 or 2 outdoor furnishings.
These tent plots could be put outside or even within cities, within the housing districts or attached to the housing districts, or wherever. What would be a very neat idea as well would be so that you could move your tent to another location without much penalty - perhaps a small fee for plot space - while still maintaining the contents of your tent.
Tents suit the adventurer lifestyle perfectly. Transient, simple, efficient and single person: this is what adventurers signed up for! There could be camps dotted around the realm, lending the lands a lived-in feel and allowing us adventurers to be out in the wild wilderness where we belong.